Hello Joseph,

the ip helper address command is normally given on the layer 3 vlan interface for the switch to forward the broadcast it receives, to another vlan as unicast. normally all cat os switches (like 6500) will have a layer 3 supervisor module installed, where you will do the intervlan routing and enabled the ip helper address command. hence there is no need to enable this on the cat of platform, normally. catos basic platforms are normally Layer 2 chassis, which will not have ip helper commands on it !!!!

Hope this helps.. all the best.

Raj